Improvement in cushion-seated valves



UNITED STATES PATENT OFFICE..

THOWAS SHAV, OF PHILADELPHIA, PENNSYLVANIA.

lMPROVEMENT IN CUSHION-SEATED VALVES.

Specification forming part of Letters Patent No. 152,l79, dated June 16, 1874; application tiled November 21, 1873.

To all whom 'it may concern 3e it known that I, THOMAS SHAW, of the city and county of Philadelphia, Pennsylvania, have invented a new and Improved Steam, Air, and Hydraulic Cushion-Seated Valve; and I hereby declare the following to be a full, clear, and exact description of the same, ret'- erence being had to the accompanying drawing, and to the letters ot' reference marked thereon.

My invention consists in theconstruction of a valve with plunger or piston heads projecting from its seat, in the manner and for the purpose hereinafter described, and in the provision of a hydraulic packing' on the top of the valve, all for the purpose hereinafter described. The object of the invention is to enable a rapid stroke ot' valve under high pressure, Without pounding or injuring the seat of th valve, and to make a tight valve under heav vvpressure In order to enable others to use and practice my invention, I will proceed to describe its construct-ion and operation.

0n reference to the accompanying drawings, which form part of this speciiication, the sketch represents a vertical section through valvebox a, of which f is the inlet end, and d the outlet-chamber. b b are tlanges, to enable bolt-ing to ordinary cap, connected with the outlet-pipe. The valve c is provided with plunger or piston heads t and u, which form part ot' the valve. hv is a thin gum disk, located on top of valve, and is secured in place by washer 'i and screw g.

rlhe valve has a long stroke during its operation, as it is required to make a stroke equal to the length ot the plunger or piston before any fluid is allowed to pass, and on its return stroke it is held suspended for a ktemporary period, and can only gently .close down upon its seat more or less rapidly in proportion as the fluid escapes around the 'pistonhead, for it will be observed that, in the return stroke the piston u, when entering its cylinder at o', and the piston t when entering its cylinder at c, there is an imprisoned iluid in all the arca of the valve-seat, for the distances equaling the length of stroke of piston, and that the imprisoned fluid can only escape by leakage around the piston, which is so slow a process that the valve is required to make a ret-urn stroke before the valve has reached its seat, the tight joint in the meantime being made by the imprisoned fluid. This enables a valve to work rapidly under heavy pressure without shock to machinery or wear to the seat.

The gum disk secures a perfectly tight joint when the valve is brought to its seat.

It will be evident that this method of cushioning the seat of valves can bek considerably modied, as, for instance, on the double-seated cornish valve, without any alteration in the result.

That I claim, and desire to secure by Letters Patent, is-

1. The plunger or piston heads u and t, projecting from the seat of valve c, in combination with the cylinders r and e, for the described purpose ot forming the cushioned scat, substantially as described.

2. The combination of a flexible disk, hf, with valve c, for the purpose set forth.

THOMAS SHAIV.

litnessesz WM. F. BREY, WM. GARWooD. 

